Days before the New York City Marathon, the United States law enforcement officials are conducting a surveillance operation on a Russian sports agent on suspicion of bribery and corruption.

Andrey Baranov, the sports agent who lives on West 104th Street in New York, has been scrutinized by officials days before one of the sport’s most prestigious races. The federal officials are looking into whether the agent conspired with American marathon organizers, including New York City Marathon officials, to allow athletes using banned substances to compete in their events.

Plainclothes agents monitoring Baranov’s prewar apartment building between Broadway and West End Avenue, includes the Federal Bureau of Investigation and the United States attorney’s office for the Eastern District of New York in Brooklyn. The law enforcement officials are exploring all possible racketeering and money-laundering offenses dating back several years and involving the organizers of marquee American track and field competitions.

In the past, Baranov has been depicted as a whistleblower who exposed cheating and corruption in track and field. The agent is yet to be charged with any crimes. The agent claimed innocence and remarked he had “absolutely not” entered doped athletes into competitions in the United States nor had he made inappropriate payments to race organizers. Baranov also said he had been unaware of the investigation by the United States law enforcement officials.

Baranov has represented dozens of notable runners, predominantly from Russia, Ukraine, Belarus, and Kyrgyzstan. Baranov has also represented, Lyubov Denisova, who was disciplined for elevated testosterone levels in 2007, months after she set the women’s course record for the Honolulu Marathon.

In a statement, the New York City Marathon organization said we will cooperate fully with the authorities if contacted. A spokesman for the NYC Marathon said that organizers had no knowledge of criminal activity within their operation. The spokesman further added no one in the organization had received a bribe from Baranov.

In May, the New York Times reported that the US Justice Department had initiated an investigation into state-sponsored doping by dozens of Russia’s top athletes. The Justice Department is planning to scrutinize anyone who might have facilitated unclean competition in the United States or who might have used the United States banking system to enable a doping scheme.

Grigory Rodchenkov, the former long-time head of Russia’s anti-doping laboratory, had communicated to the Times that the government of Russia had conducted an elaborate program to help athletes of the country use banned, performance-enhancing drugs and go undetected.

It is rumored that some of the clients of Baranov, Russian distance runners who trained under Russian national team coaches, could have been among those who received the signature cocktail of liquor and three anabolic steroids of Rodchenkov, a combination he remarked helped speed up absorption of the drugs and limit the time during which they could be detected. The claims of Rodchenkov had earlier prompted the world governing body of athletics to impose suspension on Russia’s track and field body and more than 100 Russian athletes were barred from the 2016 Summer Olympics in Rio de Janeiro after the revelations.